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/* |
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* Written by J.T. Conklin . |
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* Public domain. |
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* |
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* Changed to use fyl2xp1 for values near 1, . |
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*/ |
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.file "log.s" |
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.text |
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.align 4 |
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one: .double 1.0 |
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/* It is not important that this constant is precise. It is only |
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a value which is known to be on the safe side for using the |
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fyl2xp1 instruction. */ |
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limit: .double 0.29 |
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.text |
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.align 4 |
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.globl _log |
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.def _log; .scl 2; .type 32; .endef |
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_log: |
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fldln2 /* log(2) */ |
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fldl 4(%esp) /* x : log(2) */ |
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fld %st /* x : x : log(2) */ |
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fsubl one /* x-1 : x : log(2) */ |
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fld %st /* x-1 : x-1 : x : log(2) */ |
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fabs /* |x-1| : x-1 : x : log(2) */ |
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fcompl limit /* x-1 : x : log(2) */ |
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fnstsw /* x-1 : x : log(2) */ |
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andb $0x45, %ah |
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jz 2f |
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fstp %st(1) /* x-1 : log(2) */ |
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fyl2xp1 /* log(x) */ |
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ret |
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2: fstp %st(0) /* x : log(2) */ |
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fyl2x /* log(x) */ |
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ret |